Hydraulic transfer valve



ug- 13 1957 D. s. HARP ETAL HYDRAULIC TRANSFER VALVE 3 Sheets-Sheet l Filed Aug. 13, 1953 Maf R Mm A 7 R f l R Rw mo @s mm mm mm v 3 ooo ooe i .m :m55 Q z w 0:2191 T. Il! w. Il'. 9555 zmwmwzm NN .E oz NL.

|NvENToRs DALLAS S. HARP ROBERT R. RlcHoLT Aug. 13,y 1957 Filed Aug. 13. 1953 INVENTORS DALLAS S. HARP ROBERT R. RICHOLT A ent Aug. 13, 1957 D. s. HARP ErAL A 2,802,453

HYDRAULIC TRANSFER vALvE:

Filed Aug. 1s, 1953 s sheets-sheet s INVENTORS DALLAS S. HARP ROBERT R. RICHOLT Agent 2,802,453 Patented Aug. 13, 1957 s HYDRAULIC TRANSFER vALvE Dallas S. Harp, Van Nuys, and Robert R. Richolt, Los `Angeles, Calif., assignors to Lockheed Aircraft Corporation, Burbank, Calif. l

Appiication August 1s', 1953, serial No. 374,102r 12 claims. (c1. 121-38) This invention relates to a transfer valve for connecting either of two sources of hydraulic pressure to a device to be operated thereby and to return the used iluid to the source where it originated.

In hydraulically operated devices the function of which is critical to the use of the device, as in boosters for the aerodynamic controls of airplanes, the booster will normally be operated by a normal hydraulic system, with a standby or emergency source of hydraulic fluid independent of the ynormal hydraulic system. The transfer valve of this invention is designed to automatically switch over to the emergency source of hydraulic fluid upon failure of the normal source of pressure fluid at the same time switching the return iluid ow to the source of huid in use. With this arrangement return uid maintains each alternative source in operative condition withnanV adequate reserve of duid for the hydraulic pumps used to produce the working pressure in each system It is accordingly a prime objective of this invention to provide an improved transfer valve for switching from one source of hydraulic pressure fluid to another while maintaining each source in operative condition while in use by returning the spent fluid to the source being used to operater a hydraulically powered device. v

It is a further object of this invention to provide an improved transfer valve of the typefdcscribed that will auto matically transfer to a source of emergency hydraulic fluid upon failure of pressure in the normal source of hydraulic fluid, whereby to avoid failure or interruption in the op; eration of a critical control element such as a hydraulic booster system.

lt is also an object of this invention to provide a transfer valve of the type described wherein the valve spool or operating element is balanced between the pressures Vin the alternative sources of hydraulic pressure and operates to shift to the emergency source in response to predetermined changes in the pressure differential between said sources.

It is also an object of this invention to provide an improved hydraulic transfer Valve for switching between a normal and emergency source of hydraulic pressure lluid wherein a sleeve is shifted to connect one source or the other to the device to be hydraulically operated, and wherein one source of hydraulic pressure is used to shift and lock the sleeve into a position wherein said source is operating the device, and pressure from the alternative source of hydraulic iluid is imposed on the sleeve to unlock and shift the sleeve to bring the alternative source of hydraulic iluid into operating connection with the device upon the impairment of pressure in the normal source of hydraulic uid.

Other and further objectives of this invention will become apparent as the detailed description proceeds of one embodiment of the invention as illustrated in the accompanying drawings wherein:

Figure 1 is a longitudinal-section of a transfer valve embodying the features of this invention, the hydraulic connections thereto being schematically shown,A The 2 valve is shown as connecting the normal hydraulic system to a device operated thereby.

Figure 2 is a longitudinal section similar to Figure l showing the transfer valve shifted to the emergency source of hydraulic pressure fluid. o

Figure 3 is a, top plan view of the transfer valve of this invention.

Figure 4 is a section on the line 4-4 of Figure 1 showing the manual release for restoring operation of the normal source of pressure fluid.

As show on the drawings:

The reference number 10 indicates a valve body having a cylindrical bore 11 with siX spaced grooves in the wall thereof. Starting from the left, the iirst groove 12 is connected by a tube 13 to a source of normal hydraulic pressure fluid 14. The second groove 15 is connected by a tube 16 to a control valve 17 controlling a double acting hydraulic cylinder 18 the valve having tubes 19 and 20 connected with the two ends of the cylinder 18 The third groove 21 has a supply tube 22 from an emergency source of pressure uid 23. A fourth and widest groove 24 has a return tube 25 connecting to the normal source of hydraulic fluid 14; while the fth groove 26 is connected to a return ow tube 27 from the valve 17. The sixth and last groove 28 has a connecting tube 29 forming a return duct` to the emergency source of hydraulic uid 23. The normal and emergency fluid sources 14 and 23 are not detailed but could comprise a reservoir from which a pump draws iuid discharged through the tubes 13 and 21 with the tubes 25 and 29 returning fluid to the respective reservoirs of the separate sources of supply. The two sources of pressure Huid 14 and 23 do not necessarily provide the same working pressure and we have chosen to proportion the valve to work under 3,000 p s. i. fromthe normal system 14 and 1,500 p s. i. from the emergencysystem 23.

Shown at the bottom of the valve body 10 is a spring loaded bypass valve 30 between passages 31 and 32 connecting the grooves 15 and 26 tobypass excessive pressure in the return line 27 from the control valve 17 tothe pressure line 16 thereto" to permit manual operation of the device operated thereby upon failure of both' pressur sources. .It will be evident that this bypass valve 3l) only y opens when the pressure in line 27 exceeds that 'in line 16.

The bore 11 in the valve body accommodates a reciprocable sleeve like spool 33 with grooves 3 4 and 35 on the surface thereof. Groove 34 is so positioned as to connect either of the bore grooves 12 and 21 with the groove 15 according to the position of the spool in the bore, and groove 35 similarly connects either of the bore grooves 24 and 28 with the groove 26 As shown in Figure 1, where the spol is set foroperation with the normal hydraulic system 14, bore groove 12 is connected to groove 15 by groove 34, and groove 24 to 26 by groove 35. In Figure 2 the sleeve has been shifted so that the other grooves are connected. l

The spool 33 is normally held in the position of Figure 1 by balls 36 in holes in the sleeve which balls are forced outwardly into groove 37 in the walls of the valve bore 11 by means to be later described.

A housing 38 i-s attached to the left end of the valve body 1t). The housing 38 has an enlarged bore 39 aligned with the axis Iof the valve bore 11, and a crank chamber 40. A fluid duct 41 leads to the crank chamber from the groove 21 which receives pressure lluid from the emergency system 23, this `duct being shown in dotted lines in Figure 3. A piston 42 is reciprocable in the bore 39 and is urged to the right by emergency system pressure in the crank chamber 40 which movement is normally opposed by normal system pressure applied to the left against the effective areas of the piston and Valve spool, such4 fluid being :supplied to the bore 39 to the right of the piston by a duct 44 leading from the groove 12 aS shown in Figure 3. 'Thus when the normal and emergency system pressures are acting on either `end of the piston 42 it remains in the position of Figure l `and failure of pressure in the normal system 14 allows emergency pressure in thef'crank chamberj40 to push thepiston '41'to the right, into `the position of 'Figure 2. A Scotch yoke type of Acrosshead is formed 'by a roller 45 carriedbyia crank 46fon ashaft 47 journalled transversely of the crank chamber 40. The roller 45 operates in Ya vertical `slot 48 in one 'side of the piston, land a lever 49 attached to the shaft is connected to a remote indicator and yoperator (not shown) convenient to the jpilot Vor ight engineer. This leveris manually operated only-to brealdthetoggle 'lock formed by the position of the crank V46=as shown in Figure 2 and to close the orice valve v56. A stop screw 5.0 is vmounted :in the housing 38 in line with the piston 42 to limit Vthemovement "of the piston to the left and another stop screw/51 is Icontactedby'the Ycrank 46 in the position of VFigure 2 to prevent movement thereof past the dead 4center position of the roller 45.

VThe piston 42 carries a pilot member extending well into the -hollowf center of the valve spool 33 comprising from left to right a land 52 fitting the Vbore 11, a second land 53 with ramp shoulders 54 to lift the Ilocking balls outwardly through the spool 33, and an extension 55 carrying an `internal sleeve valve `56 controlling a restricted orice 57 through the spool 33 which opens into the groove 24 inthe valve bore "11. The ylands 52 and 53 are drilled at l53 to provide for fluid ow from a chamber 39 between the piston shoulder 43 and the land 52 into and through the spool 33 `and sleeve valve 56 so Vthat the normal system pressure is transmitted through the spool 33 to the right hand end thereof as well as acting on the dilference in areas of the piston 42 and the land 52 tending to push the latter to the left `against the pressure-of the emergency system acting in the crank chamber 40. When the piston 42 Vand internal sleeve valve 56 move to the right towards the emergency position of Figure 2, the land 53 lreleases the balls from their groove 37 in the bore 11 and the land 52 then contacts the end of the spool 33 to push it to the right.

At the same time the internal sleeve valve 56 uncovers the oritice to bleed off the normal system pressure interiorly ofV Y the spool 33 to thereturn line 25 to the normal system 14.

The right end of the valve body 10 is closed by a cap power control valve, and routing the return flow from A the power control valve to the return line to the low pressure side 25, of the normal hydraulic system. The emergency hydraulic pressure 22 and return 29 lines are shut `off from any connection with the power control valve.

The interior 'of the valve spool 33, and the piston chamber 39, arealways exposed to normal hydraulic system pressure through pasage 44 from the valve normal system pressure `inlet port 12, regardless of the valve position. In a like manner, the chamber 40 around the valve operating shaft 47, and crank 46 .is always exposed to emergency system pressure by a passage 41 to that valve inlet port 211, regardless of the valve position. lIn ti e spool position Figure l, and under normal condition, it may be seen that the 3,000 p. s. i. normal system pressure exerted on the piston 42 would overcome the 1,500 p'. s. i. emergency `system pressure in the crank chamber, and hold the valve securely in the position shown, which in turn-holds the ball locks in position, thus lockingV spool 33 inplace.

The check valve 30 sho-wn permits flow from valve 4v Y l port 26 to 15, rshort-circuiting one end of the actuator cylinderto 'the other end ofthe cylinder duringmanual operation of the control surfaces.

As the normal hydraulic system 14 pressure decreases, upon a system failure, to less than the emergency system 23 pressure in the crank chamber 40, the piston 42 engaged with the crank roller 45 :will move away from the crank chamber, 'to the right as in sFigure 2. The rst part of :such movement simultaneously brings the piston land 52to'bear upon Athe end of the main valve spool 33, and the land 53 unlocks the r`ball lock retaining 'the main spool 33 in position, and opens the orifice 57 from the interior of the Amain spool Vinto the normal hydraulic system return pressure groove 24. The opening of the `orifice 57 further decreases the pressure in the interior of the valve spool 33 and connected chamber 39, even though the normal system should recover itsI capacity and pressure of 3.,'000 p. s. Ii. The dumping of the Vpressure in the interior of the valve increases the pressuredifference on the two sides of the actuator piston42. The movement already initiated is accelerated and continues until the valve `spool comes against `its adjusting screw stop 60; the operating crank and roller come .to a dead center position; yand the main valve spool 33 is then in position for routing hydraulic uid from the high pressure side 21 of the emergency hydraulic system 23 to the `airplane surface power control valve 17, routing the return ow 27 from the power control valve tothe return, or low pressure side 29, of the emergency hydraulic system, and shutting olf the normal hydraulic system pressure 12 and return 24 grooves from, any connection with the power control valve 17. If subsequentto the `above transfer, the normal system pressure should be yrestored to 3,000 p. s. i., the pressure inside the valve spool andetfectve on the normal pressure side of the actuator piston 42 is limited by the :action of the ow restricted orifice 57 the valve main spool33. The restrictor limits the internalow through the valve lto 0.5 G. P. M., at 3,000 p. s. i. pressure supply from the normal hydraulic system.

lf, after the-transfer operation to Figure 2 as described above, thenormal system pressure and flow should recover and the emergency system pressure fail, the valve still will remain in its transferred position for emergency hydraulic system operation due to the operating crank 46 being on its dead center position.

With the valve in the emergency operating position of Figure 2, and assuming either recovery of the normal system 13 or failure of the emergency system 23, it is necessary to move the crank 46 and operating shaft 47 manually through approximately 10 away from its dead center position in order to initiate the transfer operation. The 10 manual rotation of the crank 47 is suiicient to close the orifice 57 through the side of the valve main spool 33, which brings the internal pressure in the main spool up to working pressure. With 3,000 p. s. i. on the normal pressure side and 1,500 p. s. i., or 0 p. s. i., on the emergency pressure side of the piston 42, the pressure difference creates a force in the direction to continue and complete the transfer operation. The last part of the movement of the crank and piston, after the spool movement has beenstopped by the ange 61 on the end of the spool, forces the balls 3o into the annular lock groove 37 and locks the spool in its transferred position, as shown in Figure l. The piston is stopped in its travel by a stop screw 50 in the crank chamber 40.

While we have selected 3,000 p. s. i. for the normal hydraulic system and 1,500 p. s. i. for the emergency system it will be evident that the transfer valve can be designed for other working pressures, so that we do not desire to limit ourselves to specific pressure differential.

Having thus described our invention and the present preferred embodiments thereof, we desire to emphasize the fact that many modifications may be resorted to:in a manner limited only by a Vjust interpretation of the following claims.

We claim as our invention:

l. A transfer valve adapted to connect an hydraulically operated mechanism with the pressure and return lines of two alternative sources of hydraulic pressure, the valve including a body having a bore, a first pair of ports in the wall of the bore, one port of the first pair receiving pressure from one of said sources and the other port of the first pair receiving pressure from the other source, a second pair of ports in the wall of the bore, one port of the second pair being connected with the return line of one source and the other port of said second pair being connected with the return line of said other source, a pressure port in the well of the bore, and a fluid return port in the wall of the bore, a line from the pressure port to said mechanism to conduct actuating pressure thereto, a fluid return line from said mechanism to the fluid return port, a spool movable in the bore between a first position where it connects one port of said first pair with said pressure port and connects one port of said second pair with said return port whereby said mechanism is operable by pressure from one of said sources and a second position where it connects the other port of said first pair with said pressure port and connects the other port of said second pair with said return port whereby pressure from the other source actuates said mechanism, a piston operable in the body to shift the spool from one position to the other, duct means in the body supplying pressure from one of said first pair of ports to one side of the piston and duct means in the body supplying pressure from the other of said first pair of ports to the other side of the piston so that the piston is responsive to a differential in said pressures accompanying failure of one of said sources to move the spool from said first position to said second position.

2. A transfer valve as defined in claim 1 wherein the piston is arranged for movement relative to the spool, a releasable locking means for holding the spool in said first position, and means on the piston holding the locking means actuated and releasing the locking means upon such movement of the piston.

3. A transfer valve as defined in claim 1 wherein the piston is movable relative to the spool, a releasable locking means normally holding the spool in said first position and released by movement of the piston relative to the spool, and valve means also operated by said movement of the piston relative to the spool to connect one side of the piston to a return line to increase the differential on the opposite sides of the piston.

4. A transfer valve as defined in claim 1 wherein a manually releasable means normally holds the piston against movement.

5. In combination with a hydraulically operated device having hydraulic supply and return lines and two sources of hydraulic pressure uid each having pressure and return lines, a transfer valve to simultaneously connect the pressure and return lines of either source of pressure fluid to the supply and return lines of the hydraulically operated device, said transfer valve comprising a valve body having a cylindrical bore a sleeve like valve spool shiftable in said bore, grooves in the bore and valve spool arranged to alternately connect the pressure line of either source of pressure uid to the supply line to the operated device, grooves in the bore and valve spool arranged to simultaneously connect the return line from the selected source of pressure uid to the return line from the operated device, and a hydraulic piston aligned with the valve spool, said valve body having passages from the supply lines from the two sources of pressure uid to 6 opposite sides of the hydraulic piston whereby to actuate the piston to shift the valve spool to the other source of pressure fiuid upon failure of the source of pressure uid operatively connected to the operating device.

6. A transfer valve as defined in claim 5 wherein the hydraulic piston is movable relative to the spool, locking means carried by the spool, and means carried by the hydraulic piston for actuating and releasing said sp-ool locking means.

7. A transfer valve as defined in claim 5 wherein the valve spool interior is subjected to hydraulic pressure from one of said sources, a restricted orifice through the wall of said spool in communication with the return line to said source, and valve means carried by said hydraulic piston to control said orifice.

8. A transfer Valve as defined in claim 5 wherein a manually operable crank device engages the hydraulic piston whereby when the crank is positioned on dead center the hydraulic piston is locked at one extremity of its travel.

9, A transfer valve connected between the inlet and outlet lines of an hydraulically actuated mechanism and the pressure supply lines and pressure return lines of two fluid pressure sources, the valve including a bodyhaving a bore and ports leading from said lines to the bore, a valve spool movable in the bore between a normal positionwhere it connects the supply line and return line of one source with the inlet and outlet lines respectively of said mechanism and an emergency position where is Y connects the supply line and return line of the other source with the inlet and outlet lines respectively of said mechanism, means sensitive to the differential between two applied pressures and operable when such differential reaches a given value to move said spool to the emergency position, and an arrangement of ducts for applying the pressures from said supply lines to said sensitive means so that the latter moves the spool to the emergency position when the pressure from the supply line of the first mentioned source drops appreciably.

10. A transfer valve as defined in claim 9 characterized by releasable locking means for holding the spool in said normal position, and means operable by initial action of said sensitive means for releasing the locking means. 11. A transfer valve as defined in claim 9 characterized by means for applying the pressure in a return line to said sensitive means to increase the differential thereon when actuation of said sensitive means commences.

12. A transfer valve as defined in claim 9, characterized by a manually operable crank device for holding the sensitive means in the position where the spool is in the emergency position and operable to act on the sensitive means when the pressure from the supply line of the first mentioned source returns to normal to condition the sensitive means to move the valve spool to normal position.

References Cited in the le of this patent UNITED STATES PATENTS 

